Safety and signaling apparatus, in particular for railway crossings



SAFETY AND SIGNALING APPARATUS,

IN V EN TOR- Q7 757/6 7 Patented May 16, 1939 UNITED STAT E S PATENT OFFICE Josef Fryba, Prague, Czechoslovakia Application July 8, 1936, Serial No. 89,632 In Czechoslovakia July 18, 1935 2 Claims.

In order that a signal at a railway level crossing may be given by the train itself it is necessary to fit a contact device on the track as well as a signaling device which'cooperate with one an- 5 other'andform a'unit; Various forms'of contact devices have hitherto 'been'employed for giving the necessary impulse for 'actuatingthe signaling device. Owing to the greatly differing conditions of operation, however, none of the known forms of contact apparatus ensure an impulse being given with absolute certainty.

The contact apparatus, in accordance with the invention, is mounted in afixed support between the sleepers below the track. It consists of a pressure chamber havingtwopistons of unequal diameters and of a water-tight, closed contact chamber. Ihe larger piston has a rod which bears-permanently against-the foot of the rail and thus transmits all vertical displacements of the rail inthe form of pressure to the liquid enclosed in the pressure chamber. Any movements of the rails which are due to settlement of the superstructure or rising of the fails if the sleepers bulge are not transmitted to the contact chamher. If,'however, on the sleepers becoming loose in the ballast, the rail is pressed against the superstructure owing to the pressure of a passing vehicle, or if the rail is deflected owing to the wheel pressure of a heavy vehicle, then these no effects are transmittedto the apparatus in the contact chamber. The smaller of the two pistons of the contact apparatus then acts as an equalising valve, which, merely by moving upwards and downwards, completely equalises, directly they occur, all the pressure difierences in the pressure medium in thepressure chamber. This contact apparatus does not make use of any return passages or other small passages for the pressure liquid and does not employ any valves for equalis- 40 ing the pressure, so that any danger of failure owing to such passages becoming choked or to the valves not working properly is obviated. This direct and immediate equalisation of pressure ensures that the contact apparatus always functions is properly even if fluctuations in temperature ocour and prevents the pressure vessel from being exposed to unallowably high pressures.

It will be seen, therefore, that provision is made whereby an immediate equalisation of pressure 50 is eiiected in the pressure chamber, and that the smallest movement of 'the rails, for example a movement of 0.5 mm., which is produced in practical operation by a vehicle, is directly followed by the complete and positive movement of the 55 equalising piston, for example of 15 mm., which is necessary to produce the contact action. The power exerted by the equalising piston is thereby reduced, as compared with the power exerted by the movement of the rails, proportionately to the increased displacement of this piston. As soon, 5 however, as the movement of the rail exceeds a minimum the excess movement is taken up in the pressure liquid without exerting any further action.

The apparatus in accordance with the inven- 10 tion is considerably more reliable than the known insulating rails particularly when the climatic conditions vary. The superstructure of the railway track may be arranged in any way and the shortest lengths of railscan be utilised for signal-- 15 ing purposes. The use of the contact apparatus in accordance with the invention requires considerably less invested capital and the main enance costs are verylow and no control or supervision is necessary as is required with insulating 20 rails. A signal apparatus'controlled by a contact apparatus of this kind requires incomparably less electric energy to'work itthan apparatus having an insulating rail, so that with the contact apparatus in accordance with the invention 25 a battery of accumulators can be employed as the source of energy. This circumstance considerably increases the reliability of operation and makes the operation of the apparatus independ ent of electric supply mains. The sole disadvantage of such a contact apparatus in comparison with an insulating rail is perhaps the undesired effect which a vehicle which is stationary over it might have on the apparatus by giving a second undesired impulse.

One embodiment of'the contact apparatus according to the invention is illustrated by way of example in the accompanying drawing in which:

Fig. l is a vertical axial section through the contact apparatus. 40

Fig. 2 is a view of a part ofthe apparatus on a larger scale.

Referring to Fig. l, the track-contact apparatus consists of a pressure vessel l for liquid and a water-tight contact box Z'which is directly connected to the pressure vessel I. The greater part of the pressure vessel l is charged with a liquid, for example glycerine, which is normally not under pressure and the vessel is divided by a vertical partition 3 into two cylindrical chambers l and I0. In the larger main cylinder 4 is the mainpiston 5, the piston rod 60 of which is hollow throughout its entire length and is mounted in the pressure vessel I on "a guide pipe 6!! which is supported on the bottom of the vessel l and makes a pressure-tight connection with the piston rod. The hollow space which is thus formed in the piston rod 60, the piston 5 and the guide pipe 60 encloses a helical spring M which continuously presses the head 62 of the piston rod 60 against the base I of the rail. The part of the piston rod 66 which projects out of the pressure vessel I up to the base of the rail 1 is protected from the effect of external influences, such as ballast, sand water, ice and the like, and is enclosed by a casing. The length of the piston rod 60 which is protected is adapted to suit the existing difference of level, and suitable provision is also made above the head 62 on the piston rod, so that any penetration of liquid or air into the hollow space of the piston rod is prevented under all conditions of operation of the apparatus. If the spring should break, there is no possibility of the broken parts of the spring screwing one into the other, since one broken part of the spring can only rest upon the other without any appreciable loss of length or of the strength of the spring taking place.

It is clear that horizontal movements of the rail cannot displace the piston rod out of its vertical position, while all vertical movements of the rail are transmitted in full to the piston rod.

In the form of construction according to Figure 1, the second cylindrical chamber ID of the pressure vessel 1 forms a working chamber for the compensating piston H, the diameter of which is considerably smaller than that of the piston 5 in order to obtain the desired piston movement. Thus, for example, if the ratio of the diameters of the two pistons is 7': 1, when the piston 5 makes a stroke, the smaller piston H makes a stroke which is approximately 50 times as long, the pressure effect of the latter piston being reduced in the same proportion. The working chamber NJ encloses the piston II but only makes tight contact with it over a small distance which is considerably less than the length of the entire stroke I-I, namely for only the small distance h which is equal to the width of the annular part 3' of the wall of the chamber Hi. This distance h amounts to only a small fraction, for example one-tenth, of the whole stroke H of the piston. In the normal position of the compensating piston H, therefore, the whole of the liquid present in the apparatus is separated into two independent parts, and there is no connection whatever in the form of passages or valves between these two parts of liquid. Over the remaining part of the stroke H the wall of the working chamber I0 is provided with a groove l2 of wedge-shaped cross section, or is widened out in another manner, whereby this chamber may be freely connected with the remaining space in the pressure vessel I. The working chamber l0 therefore forms a connection between the parts of the pressure vessel l above and below the main piston 5. In any position of the compensating piston II in which it is located outside the range of the ring 3, the pressure liquid can flow from the part of the chamber below the main piston 5 into the part above this piston and vice versa, whereby the difference between the pressure of the liquid in the two parts is equalized. Only after this pressure equalization has taken place is it possible for the compensating piston to return within the range of the ring 3'. The same procedure also takes place when the piston ll makes a stroke in the opposite direction. It is necessary to fix or stabilize the normal position of the compensating piston H while simultaneously allowing a possibility of movement to this piston in both directions, i. e. upwards and downwards. In order to ensure this each of these movements of the compensating piston takes place against the action of a spring. In the form of construction according to Figures 1 and 2, both the springs 63 and 64 are arranged the compensating piston ll. Each of these springs presses against a fixing socket, namely the sockets such as 65 and 6G, and holds the sockets in their normal positions which are limited by fixed stops. This arrangement could, of course, be modified in various ways. In the form of construction according to Figures 1 and 2 there is provided in the upper part of the pressure vessel 1 a cylinder 61 having its own guide sleeve 67 for its piston rod ll of the compensating piston H. The lower part of the cylinder El is provided with a recessed portion 68 (Figure 2) in which is fitted the helical spring 63 of which one end bears against the adjacent face of the sleeve 61 while the other end bears against the upper flange part of the fixing socket 65. The upper edge of the piston rod ll is provided with a flange 69 with which the piston rod ll seats itself on the lower fixing socket 655. The piston ll, Ii cannot be moved by the spring 63 to any higher position than shown in Figs. 1 and 2 because the recess 68 in the cylinder 61 does not allow further movement of the socket 65. The second helical spring 64 with its own fixing socket 66 is similarly fitted in the upper part of the cylinder but so as to work in the opposite direction. This socket 66 is also pressed against a corresponding stop 61a of the cylinder 6'? by its spring 54 and in this position seats itself on the upper end of the piston H, II' which is provided with the guide flange '69. If an under-pressure exists in the lower part of the pressure chamber, that is to say in the liquid enclosed between the two pistons 5 and Il, which may happen owing to the fact that the main piston moves upwardly owing to the return deflection of the rail l or to lifting of the rail due to cracking of the sleepers, the compensating piston I! follows the under-pressure as long as this under-pressure exists and by its displacement overcome the resistance of the lower spring 83 by which, after the pressure equalization has again been effected, it, together with its fixing socket 65, is moved upwards until the fixing socket abuts against the flange-like extension of the cylinder iii". If

1e liquid between the two pistons 5 and however, is compressed owing to sinking or deflection of the rail and the downward movement of the main piston 5 which accordingly takes place, the compensating piston ii at once yields and is moved upwards as long as there is an under-pressure below it. The piston ll, however, is only tight against its cylinder over the width of the ring 3, so that after its displacement from its normal position the liquid can flow quickly past it and equalization of pres sure, therefore, takes place very rapidly. At the end of the working chamber there is provided a free outlet for the liquid which ensures, on the one hand, that the whole of the desired upward movement of the compensating piston ii takes place even when the main piston 5 only makes a small movement, and that, when a greater deflection of the rail occurs, no unpermissibly high stresses can occur in the pressure vessel l, and that equalization of pressure is effected immediately after a pressure difference has taken place. To this end the compensating piston yields to a somewhat greater extent when the displacement of the pressure liquid is greater, and makes a somewhat greater upward movement, for example to an extent of 2 m-m., without otherwise interfering'in any way with the ordinary operation of the apparatus. The upward movement of the compensating piston constitutes also the working stroke of the apparatus, while the power derived from. the main piston 5, which is transmitted by the small compensating piston ll only in the proportion of the areas of the surfaces of the two pistons to one another, acts as the driving force for the mechanism in the second chamber, namely the mechanism in the contact chamber 2. Since the movement of the piston II proceeds very rapidly, it is necessary that the resistance opposing its movement should be as small as possible in order to minimize wear on the moving parts. Preferably, therefore, only such a fraction of this driving force as is necessary is made use 01. The actual power requirements of the contact chamber depend on its construction and on the work which it has to perform. The movements of the compensating piston II are transmitted by means of the piston rod II; and a transmission rod 8|].

What I claim is:

1. A track instrument for completing a circuit through a signaling device comprising, a chamber mounted below the track, a piston arranged in a cylindrical portion of said chamber, a second piston movably mounted in another cylindrical portion of said chamber, a fluid supply within said chamber, a partition within said cylinders having communicating passages extending respectively between the ends of the two cylinders, means for imparting vertical movements of the track to said first mentioned piston, yieldable means associated with each end of said second mentioned piston whereby the hydraulic responsive movement of said second mentioned piston is opposed by either of said yieldable means, signal switch contacts arranged for movement by said second mentioned piston, and abutments for limiting the movement of the smaller piston in response to said yieldable means.

2. A track instrument for completing a circuit through a signaling device, comprising, a chamber rigidly mounted below the track, a piston of a given diameter arranged in a cylindrical portion of said chamber, a piston of a smaller diameter than said first mentioned piston operably mounted in another cylindrical portion of said chamber, a fluid supply within said chamber, a partition in said chamber positioned between said cylinders having communicating passages between said pistons, means for imparting movements of the track to said first mentioned piston, whereby the smaller piston is hydraulically moved a greater distance than said first mentioned piston, signal switch contacts arranged for actuation by said smaller piston, the cylinder of the smaller piston fitting tightly against its piston along a portion of the length of the cylinder, said cylinder having a longitudinally extending groove in other portions of the cylinder wall, yieldable means associated with each end of the smaller piston whereby the hydraulic responsive movement of the smaller piston is opposed by either of said yieldable means, and abutments for limiting the movement of the smaller piston in response to said yieldable means.

JOSEF FRYBA. 

